Overview

Brief Summary

Biology

Hispaniolan solenodons are solitary, nocturnal and rare, and so, unsurprisingly, are rarely seen (2). They are capable of climbing near-vertical surfaces but spend most of their time searching for food on the ground. They use their flexible snout to explore cracks and crevices, and their massive claws to dig under rocks, bark and soil, for invertebrates such as beetles, crickets, insect larvae, earthworms and termites (2). The Hispaniolan solenodon is also large enough to prey on amphibians, reptiles and small birds. Indeed, local people believe it to eat snakes and chickens (4), and such remains have been found in solenodon faeces, although this may be the result of scavenging dead animals (2). It lunges at its chosen prey, pinning it down with its strong forelimbs, and then scoops up the prey with its lower jaw. A bite from the solenodon injects the victim with toxic saliva and renders the prey immobile (2). Before Europeans arrived on the island, the solenodon would have been one of the dominant carnivores on Hispaniola, and was probably only eaten occasionally by boas and birds of prey (2). Unfortunately, the situation is very different today. Solenodons have a long life span, possibly around 11 years, and a low reproductive rate. The female gives birth to one or two young in a burrow (2), which can be an extensive system of tunnels in which they forage and nest (3). During the first two months of life the young remain close to their mother and may accompany her on foraging excursions, hanging on to her elongated teats by their mouth (2).

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Description

This ancient and distinctive mammal, capable of secreting toxic saliva, faces very real and immediate threats to its survival (2). One of only two solenodons in existence, it resembles a large, stocky shrew, and has a distinctive, elongated snout that extends well beyond the jaw. A unique ball-and-socket joint attaches the snout to the skull allowing remarkable flexibility and mobility (2). The Hispaniolan solenodon has coarse grizzled grey-brown fur with a black forehead and yellowish flanks (2) (3). On the nape of the neck is a white spot. The stiff, muscular tail is grey except for the base and tip which are whitish. The well developed forelimbs bear long, stout, sharp claws (2), and it walks with a stiff, waddling gait with only its toes coming into contact with the ground (3).

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Physical Description

Morphology

Solenodon paradoxus looks much like a shrew. However, it is considerably larger. A black to reddish-brown pelage covers the majority of the body, with the exception of the tail, feet, nose, and tips of the ears. The forelimbs are considerably more developed than the hindlegs, but all limbs have claws presumably for digging.

Its heads is large in proportion to its body and the rostrum is elongated. A defining characteristic of Solenodon paradoxus is the os proboscis, a bone (which supports a long cartilaginous snout) located on the tip of the rostrum. This species' dental formula is 3/3, 1/1, 3/3, 3/3 = 40. The second lower incisor has a groove from which a venom is secreted from a mandibular gland.

Males of this species have an unexposed penis and testes residing deep within the abdominal cavity.

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Ecology

Habitat

Habitat and Ecology

The Haitian solenodon is found in forests and brush country, as well as around plantations. It is mainly nocturnal, hiding during the day in rock clefts, hollow trees, or burrows which it excavates itself. Its diet includes insects and spiders found in soil and leaf litter. Solenodons obtain food by rooting in the ground with their snouts and by tearing into rotten logs and trees with their foreclaws. This species is relatively social, and up to eight individuals may inhabit the same burrow. Litter size is 1 or 2 young. The young are born in a nesting burrow. Young solenodons remain with their mother for several months, which is exceptionally long for insectivores.

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Solenodon paradoxus can be found in wooded and brushy areas, often near areas of agriculturally developed land. Because solenodons are nocturnal they find shelter during the day in tunnel systems that they construct by burrowing through organic material and soil. They also take refuge in hollowed logs and trees, caves, and cracks in rocks.

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Trophic Strategy

Reports conflict on whether Solenodon paradoxus consumes vegetation, along with their standard diet of invertebrates. Walker's Mammals of the World states that members of the genus Solenodon feeds on various fruits and vegetables. However, a study conducted by Erna Mohr found that solenodons refused all forms of vegetation. From this study, a list of items included in the diet of members of the genus Solenodon's was compiled from fecal analysis (Fons, 1990). This list is shown below. Solenodon paradoxus collects food by digging extensive tunnel systems under the ground, then foraging for insects and other invertebrates from the surrounding soil.

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Associations

Because of the small numbers of Solenodon paradoxus, it barely contributes, if at all, to its ecosystem. If Solenodon paradoxus were present in greater numbers it might effect the populations of insects and other invertebrates that it preys upon. Furthermore, its extensive burrowing and tunneling might contribute to soil aeration.

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Before the European colonization of Hispanolia, which has resulted in the introduction of several predators of solenodons the island, Solenodon paradoxus was one of the dominant predators on Hispaniola. In fact, to this day, it lacks any truly natural predators and does not possess many anti-predator adaptations. Solenodon paradoxus is described as a "slow mover" and a "clumsy runner with no agility in avoiding enemies and a poor means of defense" (International Wildlife Encyclopedia, 1974). It has been observed sitting still, with its head hidden, while predators are in pursuit.

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Life Expectancy

There is very little information concerning the lifespan/longevity of Solenodon paradoxus. John F. Eisenberg cited a specimen that lived in captivity for 11 years and four months, the longest recorded lifespan of this species (Nowak, 1999).

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Reproduction

Little is known about the mating system and behavior of Solenodon paradoxus. Before mating, the female constructs a nest in which she will birth and nurse her young. It is known that females have an estrus period that irregular and not coordinated with the seasons. Males, in contrast can mate at any time. When first introduced to each other, solendons may engage in aggressive behavior, but it is unknown whether this is an attempt at sexual dominance.

Mating System: polygynandrous (promiscuous)

Very little is known about the reproductive behavior of Solenodon paradoxus. This species breeds at an extremely slow rate, only twice per year. Newborns weigh from 40 to 55 grams and are 15.2 to 16.3 cm in length, with little hair and closed eyes (Fons, 1990). The information below was provided by Asdell's Patterns of Mammalian Reproduction (Hayssen, et al, 1993).

The number of young that can survive is limited to the small number, two, of teats the female possesses. These are on her dorsal side, near the rump (International Wildlife Encyclopedia, 1974). Young are nursed for 13 weeks, at which time they begin to eat solid food. Solenodon paradoxus is born with only a minimal layer of hair, barely covering its body. A more dense coat fills in within 14 days. After 75 days, a young is no longer nursing and is eating solid food.

Listed as Endangered because its area of occupancy is estimated to be less than 500 km, its range is severely fragmented, it is restricted to forest habitats, and there has been an observed shrinkage in its distribution and anecdotal information on habitat destruction and degradation within its range, and a decline in the number of individuals due to invasive species and persecution.

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As late as the 1960's, Solenodon paradoxus was not considered to be in any danger of extinction. However, in more recent years, the decline of suitable forest habitat through deforestation, an increase of human activity in their habitat, and the introduction of new predators (domesticated canines and felines) have contributed to the enormous decrease this species' numbers.

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Trends

Population

This species is rare. In Haiti the species could be considered Critically Endangered because there is an isolated population with a range less than 100 km, threatened by habitat loss and persecution (S. Turvey and L. Davalos pers. comm.).

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Threats

The most significant threat to this species appears to be the continuing demise of its forest habitat and predation by introduced rats, mongoose, cats and dogs, especially in the vicinity of settlements. In Haiti persecution and hunting for food (Samuel Turvey pers. comm.) is a threat, and there is devastating habitat destruction also occurring.

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Once one of the dominant carnivores on Hispaniola, the solenodon is now greatly threatened by predation from introduced cats, dogs and mongooses brought to the island with the arrival of the Europeans (1) (2). Even back in 1907, when a Mr Verill attempted to find the solenodon in the Dominican Republic, he attributed its restricted range to the presence of the mongoose, and felt that it was only a question of time before the mongoose would cause the solenodon's extinction (4). The destruction of forests on the island poses another significant threat to the solenodon, an animal which is particularly vulnerable to any negative impact due to its low reproductive rate (1) (2).

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Management

Conservation Actions

It is protected by law in the Dominican Republic (General Environmental Law 64 - 00). There is a recovery Plan published in 1992 which suggested comprehensive surveys, and management in the National Park Pic Macaya, and education, and the control of exotic mammals, and breeding programmes. At the moment it is not being implemented (Samuel Turvey pers. comm.). It is found in most protected areas in the Dominican Republic (Sixto Inchaustegui pers. comm.). It is one of the species that lives in both the Caribbean Biodiversity Hotspot and the Greater Antillean Moist Forests Ecoregion (Olson and Dinerstein, 1998).

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Conservation

There is thought to be little hope for this species in Haiti (2), but in the Dominican Republic, the Hispaniolan solenodon occurs in the Madre de las Aguas Conservation Area and Del Este National Park (5). These areas still face threats from logging, agriculture and cattle ranching, however conservation organisations, such as The Nature Conservancy, are working to address these threats and implement management plans for protected areas (5). Whilst the focus of efforts should be to conserve this species in protected forest reserves, the enormous pressure from increasing human populations on Hispaniola may mean the survival of this unique mammal ultimately depends on zoos (2).

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Relevance to Humans and Ecosystems

Benefits

Because of its small numbers, Solenodon paradoxus is incapable of causing any significant detriment to the human economy. When it was present in higher numbers, farmers reported destruction of crops as a result of solenodon activity. However, this crop destruction was incidental to the solenodon's predation on insects beneath the soil.

The Hispaniolan solenodon looks much like an oversized shrew. It weighs 0.6–1.0 kg (1.3–2.2 lb). Head-and-body length is 28–33 cm (11–13 in) and the tail is about 25 cm. It has brownish-red fur on most of its body, with a paler underside. The tail, legs, snout, and eartips are hairless. The forelegs are noticeably more developed than the hind legs, but all have strong claws useful for digging.

The head is very big in relation to its body, with a long rostrum and tiny eyes and ears partially hidden by the body fur. A unique feature is the os proboscis, a bone on the tip of the rostrum that supports the snout cartilage. The dental formula for the species is 3/3, 1/1, 3/3, 3/3 = 40. The second lower incisor has a narrow groove (Solenodon derives from the Greek for "grooved tooth"), through which flows a venomous saliva secreted by the submaxillary gland, making the solenodon one of only a handful of venomous mammals.

Both sexes are similar. Males have an unexposed penis and the testes are hidden deep within the abdominal cavity. Females have an irregular estrus, apparently unrelated to seasonal changes; they may have two litters of one to three young per year. Usually, only two of the offspring survive, because the female only has two teats, which are found near her buttocks. The young are weaned after 75 days, but may sometimes remain with the parents while subsequent litters are born and raised, so up to eight animals may share the same burrow. Solenodons may fight each other on first meeting, but eventually they establish a dominance relationship and live together in captivity in relative harmony.

A Hispaniolan solenodon has glands in the armpits and in the groin, which are said to give off a goat-like smell. It readily defends itself against one of its own kind and is apparently not immune to its own venom, since animals have been seen to die after fighting and sustaining minor wounds. It may also attack other animals savagely: a captive solenodon was reported to have attacked a young chicken and torn it to pieces with its strong claws before eating it. In moments of excitement, it may grunt like a pig or give bird-like cries, but when pursued, it stays motionless and hides its head, making it easy to capture.

The Hispaniolan solenodon was unknown to science for so long because it is nocturnal, a consequence of which is its highly developed senses of hearing, smell and touch. Also, they are not very numerous, so their influence in an ecosystem is practically nothing. During daylight hours, they stay in their burrows, trees, hollowed-out logs or caves, remaining hidden from view. When they do come out, they run on their toes with a stiff, ungainly waddle, following an erratic, almost zigzag course. The local people claim solenodons never run in a straight line. When a solenodon is alarmed and tries to move faster, it is very likely to trip.

Hispaniolan solenodons eat a wide variety of animals, including arthropods, worms, snails and small reptiles; they may also feed on roots, fruits and foliage, although one study found they refused all forms of vegetation.[citation needed] They probe the earth with their snouts and dig or rip open rotten logs with their claws. Solenodons in captivity have been seen to bathe often and to drink only when bathing.

Because of a lack of natural enemies, the Hispaniolan solenodon did not evolve defenses against predators, and it is a slow, clumsy runner. When feral dog and cat populations became established and small Asian mongooses (specifically Herpestes javanicus auropunctatus) were introduced to control rats in sugar cane fields, its future was jeopardized.

The Hispaniolan solenodon's habitat is usually wooded or brushy areas, frequently close to developed agricultural land, where they can dig their complex underground burrows. Habitat loss and predation by introduced species have contributed to making it an endangered species; its numbers have dropped dramatically during the last few decades. It was actually considered almost extinct until 1907, when it was found living in the interior of Hispaniola. It was not considered to be in immediate danger early in the 20th century. In 1966, it was found in several localities in the Dominican Republic. As of 1981, after extensive searching, the Hispaniolan solenodon was declared "functionally extinct"[clarification needed] in Haiti, persisting only in the remote mountains of the south. In 1987, it was still found in both countries, but was thought to be particularly threatened in Haiti. As of 1996, it could still be found in both countries. Wildlife filmmaker Jürgen Hoppe has been able to film the Hispaniolan solenodon in various parts of the Dominican Republic during the last 18 years.[when?] The most recent sightings in the wild (with video evidence) were during the summer of 2008, when a team of researchers from the Durrell Wildlife Conservation Trust and the Ornithological Society of Hispaniola were able to trap an individual specimen. The researchers took physical measurements and DNA from it before releasing it back into the wild.[3]

The Hispaniolan solenodon was identified as one of the top ten "focal species" in 2007 by the EDGE Species project.[5] A collaborative conservation project funded by the Darwin Initiative (UK) was started in 2009 and is researching the species to conserve it.[6]

The species is fully protected by law. However, national parks in both the Dominican Republic and Haiti are threatened by deforestation and encroachment for farming and charcoal production. The US Agency for International Development and the Nature Conservancy are[when?] working with local nongovernmental organisations to improve protection and implement management plans for these parks (the "Parks in Peril" programme). A recovery plan for the isolated Haitian population, published in 1992, advocated comprehensive surveys, improved management of the Pic Macaya National Park, education campaigns, control of exotic mammals, and an ex situ breeding programme. These recommendations have not yet[when?] been implemented.

Two conservation research and education programmes funded by the Darwin Initiative have recently been established, focusing on solenodons in both the Dominican Republic and Haiti: "Building evidence and capacity to conserve Hispaniola's endemic land mammals" (started 2009), and "Building a future for Haiti's unique vertebrates" (started 2010). These collaborative projects represent a partnership between the EDGE programme, the Durrell Wildlife Conservation Trust, BirdLife International, the Sociedad Ornitologica de la Hispaniola, the Dominican Republic National Zoo, Societe Audubon Haiti, and in-country project partners.